Le trouble déficit de l’attention hyperactivité (TDAH) est associé à des comorbidités neurodéveloppementales et psychiatriques tout au long de la vie avec un profil des troubles associés qui tend à se complexifier avec le temps. Cet article propose une synthèse à propos des principales comorbidités et diagnostics différentiels du TDAH dans l’objectif de donner des repères et faciliter la démarche diagnostique et thérapeutique. Chez l’adolescent et l’adulte, il est fréquent que les symptômes de TDAH soient difficiles à repérer devant un trouble abus de substances ou un trouble de l’humeur. Il est pourtant important de diagnostiquer le TDAH car son traitement peut améliorer de façon décisive le fonctionnement social et le pronostic des personnes atteintes par des comorbidités. La plupart des troubles comorbides sont également des diagnostics différentiels du TDAH, avec un certain nombre de symptômes pouvant être communs entre plusieurs catégories diagnostiques. C’est le cas des difficultés de concentration, de l’impulsivité et de l’irritabilité par exemple. L’analyse clinique des comorbidités et diagnostics différentiels du TDAH nécessite une anamnèse développementale précise. Les croisements de données issues de plusieurs informateurs et les entretiens semi-structurés sont généralement une aide précieuse pour le clinicien. L’établissement des stratégies thérapeutiques pour un TDAH avec une ou plusieurs comorbidités nécessite de déterminer quel trouble est le plus invalidant. Le projet thérapeutique procède donc par étapes avec des réévaluations successives.

Attention Deficit Hyperactivity Disorder (ADHD) is associated with neurodevelopmental and psychiatric comorbidities throughout life, with a profile of co-occurring disorders that tend to become more complex over time. This article synthesizes the main comorbidities and differential diagnoses of ADHD to provide guidance and facilitate the diagnostic and therapeutic process. In adolescents and adults, it is common for ADHD symptoms to be difficult to spot amid substance abuse disorders or mood disorders. However, diagnosing ADHD is crucial because its treatment can decisively improve social functioning and prognosis for individuals with comorbidities. Most comorbid disorders also serve as differential diagnoses for ADHD, with several symptoms that can be shared across multiple diagnostic categories. This is the case with difficulties in concentration, impulsivity, and irritability, for example. Comorbidities of ADHD in children and adolescents include neurodevelopmental disorders such as autism spectrum disorder (ASD), intellectual developmental disorder (IDD), communication disorders, specific learning disorders, and motor development disorders. A meta-analysis found a lifetime prevalence of ADHD in ASD to be 40,2%, and in children with ADHD, a co-occurrent diagnosis of ASD is found in 20 to 30% [1Hollingdale J., Woodhouse E., Young S., Fridman A., Mandy W. Autistic spectrum disorder symptoms in children and adolescents with attention-deficit/hyperactivity disorder: a meta-analytical review Psychol Med 2020 ;  50 (13) : 2240-2253 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 2Simonoff E., Pickles A., Charman T., Chandler S., Loucas T., Baird G. Psychiatric disorders in children with autism spectrum disorders: prevalence, comorbidity, and associated factors in a population-derived sample J Am Acad Child Adolesc Psychiatry 2008 ;  47 (8) : 921-929 [inter-ref]

Cliccare qui per andare alla sezione Riferimenti]. The diagnostic process can be delayed in people with both ADHD and ASD. While treatment of ADHD has documented efficacy in this population, a slow titration is recommended to minimise the risk of side effects [3Young S., Hollingdale J., Absoud M., Bolton P., Branney P., Colley W., e al. Guidance for identification and treatment of individuals with attention deficit/hyperactivity disorder and autism spectrum disorder based upon expert consensus BMC Med 2020 ;  18 : 1-29 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti]. The prevalence of ADHD in children with Intellectual Disability is 39%, with higher figures in syndromic conditions such as fragile X [4Buckley N., Glasson E.J., Chen W., Epstein A., Leonard H., Skoss R., e al. Prevalence estimates of mental health problems in children and adolescents with intellectual disability: A systematic review and meta-analysis Aust N Z J Psychiatry 2020 ;  54 (10) : 970-984 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti]. Externalizing disorders such as oppositional defiant disorder (ODD) and conduct disorder (CD) associated with ADHD strongly influence psychosocial functioning and prognosis. Oppositional defiant disorder (ODD) is frequent in children and adolescents with ADHD, about 40 to 60% in clinical samples and 20 to 30% in the general population. Internalizing and stress-related disorders are also frequent in persons with ADHD at different ages. The presence of ADHD increases the risk of being exposed to accidents and other potentially traumatising life events. ADHD is a risk factor for post-traumatic stress disorder, with rates four times higher compared with controls [5Spencer A.E., Faraone S.V., Bogucki O.E., Pope A.L., Uchida M., Milad M.R., e al. Examining the association between posttraumatic stress disorder and attention-deficit/hyperactivity disorder: a systematic review and meta-analysis J Clin Psychiatry 2016 ;  77 (1) : 6862

Cliccare qui per andare alla sezione Riferimenti]. Anxiety disorders can begin at a young age with separation anxiety disorder or generalised anxiety disorder and affect about 50% adults with ADHD [6Quenneville A.F., Kalogeropoulou E., Nicastro R., Weibel S., Chanut F., Perroud N. Anxiety disorders in adult ADHD: A frequent comorbidity and a risk factor for externalizing problems Psychiatry Res 2022 ;  310 : 114423

Cliccare qui per andare alla sezione Riferimenti]. In adults with ADHD, depressive disorders are 3 to 5 times more likely than in controls [7Solberg B.S., Halmøy A., Engeland A., Igland J., Haavik J., Klungsøyr K. Gender differences in psychiatric comorbidity: a population-based study of 40 000 adults with attention deficit hyperactivity disorder Acta Psychiatrica Scandinavica 2018 ;  137 (3) : 176-186 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti]. The association between a mood disorder and impulsivity increases the risk of suicidal behaviours [8Fuller-Thomson E., Rivière R.N., Carrique L., Agbeyaka S. The dark side of ADHD: Factors associated with suicide attempts among those with ADHD in a national representative Canadian sample Arch suicide Res 2022 ;  26 (3) : 1122-1140 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti]. Bipolar disorder is found in 15% of adults with ADHD and is likely to be associated with an early onset, a more severe course and substance use disorder [9Schiweck C., Arteaga-Henriquez G., Aichholzer M., Edwin Thanarajah S., Vargas-Cáceres S., Matura S., e al. Comorbidity of ADHD and adult bipolar disorder: A systematic review and meta-analysis Neurosci Biobehav Rev 2021 ;  124 : 100-123 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti]. Personality disorders are also prevalent conditions in adults with ADHD with a prevalence of 20%. Maladaptive personality traits are often preceded by externalising symptoms during adolescence. Borderline personality disorder is more frequent in females, whereas males with ADHD more often present with narcissistic or antisocial personality disorders [10Jacobsson P., Hopwood C.J., Söderpalm B., Nilsson T. Adult ADHD and emerging models of maladaptive personality: a meta-analytic review BMC Psychiatry 2021 ;  21 : 1-16

Cliccare qui per andare alla sezione Riferimenti]. Clinical analysis of comorbidities and differential diagnoses of ADHD requires a precise developmental history. Cross-referencing data from multiple informants and conducting semi-structured interviews are typically valuable aids for clinicians. Establishing therapeutic strategies for ADHD with one or more comorbidities requires determining which disorder is most debilitating. Therefore, the therapeutic project proceeds in stages with successive reassessments. In summary, ADHD is often accompanied by various neurodevelopmental and psychiatric comorbidities, which can complicate diagnosis and treatment. A thorough clinical evaluation, including developmental history, cross-referencing of information, and consideration of differential diagnoses, is essential for accurate diagnosis and effective management of ADHD and its comorbidities.